Bioactive peptides and peptide derivatives of parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP)

ABSTRACT

Novel parathyroid hormone peptide (PTH) and parathyroid hormone related peptide (PTHrP) or derivatives thereof which are biologically active are disclosed, as are pharmaceutical compositions containing such peptides, and synthetic and recombinant methods for producing such peptides. Also disclosed are methods for treating mammalian conditions characterized by decreases in bone mass using therapeutically effective pharmaceutical compositions containing such peptides. Also disclosed are methods for screening candidate compounds of the invention for antagonistic or agonistic effects on parathyroid hormone receptor action. Also disclosed are diagnostic and therapeutic methods of such compounds.

This application is a divisional of U.S. application Ser. No.09/421,379, filed on Oct. 20, 1999, now U.S. Pat. No. 6,495,662, whichclaims the benefit of the filing date of provisional application No.60/105,530 filed on Oct. 22, 1998, which is herein incorporated byreference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSOREDRESEARCH AND DEVELOPMENT

Part of the work performed during development of this invention utilizedU.S. Government funds. The U.S. Government has certain rights in thisinvention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to novel parathyroid hormone peptide (PTH)derivatives and to novel parathyroid hormone-related peptide (PTHrP)derivatives. In particular, the invention relates to PTH and PTHrPminimized peptide and derivatives thereof that still retain biologicalactivity.

2. Description of Related Art

Parathyroid hormone (PTH) is a major regulator of calcium homeostasiswhose principal target cells occur in bone and kidney. Regulation ofcalcium concentration is necessary for the normal function of thegastrointestinal, skeletal, neurologic, neuromuscular, andcardiovascular systems. PTH synthesis and release are controlledprincipally by the serum calcium level; a low level stimulates and ahigh level suppresses both hormone synthesis and release. PTH, in turn,maintains the serum calcium level by directly or indirectly promotingcalcium entry into the blood at three sites of calcium exchange: gut,bone, and kidney. PTH contributes to net gastrointestinal absorption ofcalcium by favoring the renal synthesis of the active form of vitamin D.PTH promotes calcium resorption from bone indirectly by stimulatingdifferentiation of the bone-resorbing cells, osteoclasts. It alsomediates at least three main effects on the kidney: stimulation oftubular calcium reabsorption, enhancement of phosphate clearance, andpromotion of an increase in the enzyme that completes synthesis of theactive form of vitamin D. PTH exerts these effects primarily throughreceptor-mediated activation of adenylate cyclase and phospholipase C.

Disruption of calcium homeostasis may produce many clinical disorders(e.g., severe bone disease, anemia, renal impairment, ulcers, myopathy,and neuropathy) and usually results from conditions that produce analteration in the level of parathyroid hormone. Hypercalcemia is acondition that is characterized by an elevation in the serum calciumlevel. It is often associated with primary hyperparathyroidism in whichan excess of PTH production occurs as a result of a lesion (e.g.,adenoma, hyperplasia, or carcinoma) of the parathyroid glands. Anothertype of hypercalcemia, humoral hypercalcemia of malignancy (HHM) is themost common paraneoplastic syndrome. It appears to result in mostinstances from the production by tumors (e.g., squamous, renal, ovarian,or bladder carcinomas) of a class of protein hormone which shares aminoacid homology with PTH. These PTH-related proteins (PTHrP) appear tomimic certain of the renal and skeletal actions of PTH and are believedto interact with the PTH receptor in these tissues. PTHrP is normallyfound at low levels in many tissues, including keratinocytes, brain,pituitary, parathyroid, adrenal cortex, medulla, fetal liver,osteoblast-like cells, and lactating mammary tissues. In many HHMmalignancies, PTHrP is found in the circulatory system at high levels,thereby producing the elevated calcium levels associated with HHM.

The pharmacological profiles of PTH and PTHrP are nearly identical inmost in vitro assay systems, and elevated blood levels of PTH (i.e.,primary hyperparathyroidism) or PTHrP (i.e., HHM) have comparableeffects on mineral ion homeostasis (Broadus, A. E. & Stewart, A. F.,“Parathyroid hormone-related protein: Structure, processing andphysiological actions,” in Basic and Clinical Concepts, Bilzikian, J. P.et al., eds., Raven Press, New York (1994), pp.259–294; Kronenberg, H.M. et al., “Parathyroid hormone: Biosynthesis, secretion, chemistry andaction,” in Handbook of Experimental Pharmacology, Mundy, G. R. &Martin, T. J., eds., Springer-Verlag, Heidelberg (1993), pp. 185–201).The similarities in the biological activities of the two ligands can beexplained by their interaction with a common receptor, the PTH/PTHrPreceptor, which is expressed abundantly in bone and kidney (Urena, P. etal., Endocrinology 134:451–456 (1994)).

Native human parathyroid hormone is an unmodified polypeptide of 84amino acids. It is secreted from the parathyroid glands in response tolow blood calcium levels and acts on osteoblast (bone-building cells) inbone, and on tubular epithelial cells of kidney. The hormone interactswith a cell surface receptor molecule, called the PTH-1 receptor orPTH/PTHrP receptor, which is expressed by both osteoblast and renaltubular cells. PTHrP, the major cause of the humoral hypercalcemia ofmalignancy, also has normal functions that include roles in development.PTHrP has 141 amino acids, though variants also occur that result fromalternative gene splicing mechanisms. PTHrP plays a key role in theformation of the skeleton through a process that also involves bindingto the PTH-1 receptor (Karaplis, A. C., et al., Genes and Dev. 8:277–289(1994) and Lanske, B., et al., Science 273:663–666 (1996)).

The PTH-1 receptor is homologous in primary structure to a number ofother receptors that bind peptide hormones, such as secretin (Ishihara,T. et al., EMBO J. 10:1635–1641 (1991)), calcitonin (Lin, H. Y. et al.,Science 254:1022–1024 (1991)) and glucagon (Jelinek, L. J. et al.,Science 259:1614–1616 (1993)); together these receptors form a distinctfamily called receptor family B (Kolakowski, L. F., Receptors andChannels 2:1–7 (1994)). Within this family, the PTH-1 receptor isunique, in that it binds two peptide ligands and thereby regulates twoseparate biological processes. A recently identified PTH receptorsubtype, called the PTH-2 receptor, binds PTH but not PTHrP (Usdin, T.,et al., J. Biol. Chem. 270:15455–15458 (1995)). This observation impliedthat structural differences in the PTH and PTHrP ligands determinedselectivity for interaction with the PTH-2 receptor. The PTH-2 receptorhas been detected by RNA methods in the brain, pancreas and vasculature,however, its biological function has not been determined (Usdin, T., etal., J. Biol. Chem. 270:15455–15458 (1995)). It is hypothesized that thefamily B receptors use a common molecular mechanism to engage their owncognate peptide hormone (Bergwitz, C., et al., J. Biol. Chem.271:26469–26472 (1996)).

The binding of either radiolabeled PTH(1–34) or PTHrP(1–36) to the PTH-1receptor is competitively inhibited by either unlabeled ligand (Jüppner,H. et al., J. Biol. Chem. 263:8557–8560 (1988); Nissenson, R. A. et al.,J. Biol. Chem. 263:12866–12871 (1988)). Thus, the recognition sites forthe two ligands in the PTH-1 receptor probably overlap. In both PTH andPTHrP, the 15–34 region contains the principal determinants for bindingto the PTH-1 receptor. Although these regions show only minimal sequencehomology (only 3 amino acid identities), each 15–34 peptide can blockthe binding of either PTH(1–34) or PTHrP(1–34) to the PTH-1 receptor(Nussbaum, S. R. et al., J. Biol. Chem. 255:10183–10187 (1980);Caulfield, M. P. et al., Endocrinology 127:83–87 (1990); Abou-Samra,A.-B. et al., Endocrinology 125:2215–2217 (1989)). Further, the aminoterminal portion of each ligand is required for bioactivity, and theseprobably interact with the PTH-1 receptor in similar ways, since 8 of 13of these residues are identical in PTH and PTHrP.

Both PTH and PTHrP bind to the PTH-1 receptor with affinity in the nMrange; the ligand-occupied receptor transmits a “signal” across the cellmembrane to intracellular effector enzymes through a mechanism thatinvolves intermediary heterotrimeric GTP-binding proteins (G proteins).The primary intracellular effector enzyme activated by the PTH-1receptor in response to PTH or PTHrP is adenylyl cyclase (AC). Thus, PTHinduces a robust increase in the “second messenger” molecule, cyclicadenosine monophosphate (cAMP) which goes on to regulate the poorlycharacterized “downstream” cellular processes involved inbone-remodeling (both bone formation and bone resorption processes). Incertain cell-based assay systems, PTH can stimulate effector enzymesother than AC, including phospholipase C (PLC), which results inproduction of inositol triphosphate (IP₃), diacylglycerol (DAG) andintracellular calcium (iCa²⁺). The roles of these non-cAMP secondmessenger molecules in bone metabolism are presently unknown.

Osteoporosis is a potentially crippling skeletal disease observed in asubstantial portion of the senior adult population, in pregnant womenand even in juveniles. The disease is marked by diminished bone mass,decreased bone mineral density (BMD), decreased bone strength and anincreased risk of bone fracture. At present, there is no effective curefor osteoporosis, though estrogen, calcitonin and the bisphosphonates,etidronate and alendronate are used to treat the disease with varyinglevels of success through their action to decrease bone resorption.Since parathyroid hormone regulates blood calcium and the phosphatelevels, and has potent anabolic (bone-forming) effects on the skeleton,in animals (Shen, V., et al., Calcif. Tissue Int. 50:214–220 (1992);Whitefild, J. F., et al., Calcif. Tissue Int. 56:227–231 (1995) andWhitfield, J. F., et al., Calcif. Tissue Int. 60:26–29 (1997)) andhumans (Slovik, D. M., et al., J. Bone Miner. Res. 1:377–381 (1986);Dempster, D. W., et al., Endocr. Rev. 14:690–709 (1993) and Dempster, D.W., et al., Endocr. Rev. 15:261 (1994)) when administeredintermittently, PTH, or PTH derivatives, are prime candidates for newand effective therapies for osteoporosis.

Truncated PTH derivatives such as PTH(1–34) and PTH(1–31) are active inmost assay systems and promote bone-formation (Whitefild, J. F., et al.,Calcif. Tissue Int. 56:227–231 (1995); Whitfield, J. F., et al., Calcif.Tissue Int. 60:26–29 (1997); Slovik, D. M., et al., J. Bone Miner. Res.1:377–381 (1986); Tregear, G. W., et al., Endocrinology 93:1349–1353(1973); Rixon, R. H., et al., J. Bone Miner. Res. 9:1179–1189 (1994);Whitfield, J. F. and Morley, P., Trends Pharmacol. Sci. 16:372–386(1995) and Whitfield, J. F., et al., Calcif. Tissue Int. 58:81–87(1996)). But these peptides are still too large for efficientnon-parenteral delivery and low cost. The discovery of an even smaller“minimized” version of PTH or PTHrP would be an important advance in theeffort to develop new treatments for osteoporosis.

PTH and PTHrP derivatives that have amino acid substitutions ordeletions in the 1–14 region usually exhibit diminished activity(Tregear, G. W., et al., Endocrinology 93:1349–1353 (1973); Goltzman,D., et al., J. Biol. Chem. 250:3199–3203 (1975); Horiuchi, N., et al.,Science 220:1053–1055 (1983) and Gardella, T. J., et al., J. Biol. Chem.266:13141–13146 (1991))

Several short NH₂-terminal PTH or PTHrP peptides have been investigatedpreviously, but no activity was detected. For example, bPTH(1–12) wasinactive in adenylyl cyclase assays performed in rat renal membranes(Rosenblatt, M., “Parathyroid Hormone: Chemistry and Structure-ActivityRelations,” in Pathobiology Annual, Ioachim, H. L., ed., Raven Press,New York (1981), pp. 53–84) and PTHrP(1–16) was inactive in AC assaysperformed in Chinese hamster ovary (CHO) cells expressing the cloned ratPTH-1 receptor (Azurani, A., et al., J. Biol. Chem. 271:14931–14936(1996)). It has been known that residues in the 15–34 domain of PTHcontribute importantly to receptor binding affinity, as the PTH(15–34)fragment binds weakly to the receptor, but this peptide does notactivate AC (Naussbaum, S. R., et al., J. Biol. Chem. 255:10183–10187(1980) and Gardella, T. J., et al., Endocrinology 132:2024–2030 (1993)).

SUMMARY OF THE INVENTION

The relatively large size of native PTH or PTHrP presents challenges tothe use of these peptides as treatments for osteoporosis. In general, aprotein of this size is not suitable for use as a drug, since it cannotbe delivered effectively by simple methods such as nasal inhalation.Instead, injection is required, and in the case of PTH, daily, or almostdaily injections would most likely be needed to achieve increases inbone formation rates. Additionally, larger peptides are technicallydifficult and expensive to prepare by conventional synthetic chemistrymethods. Alternative methods employing recombinant DNA and cell-basedexpression systems are also expensive, potentially vulnerable tocontamination by foreign proteins and do not circumvent the deliveryproblem.

Accordingly, it would be advantageous for those skilled in the art to beable to identify a small molecule analog (either peptide or non-peptide)that is based on the larger peptide and yet which still retains thedesired biological activities. The activity may at first be weakrelative to the intact peptide, but further optimization can lead toenhanced efficacy and potency.

The present invention relates to PTH(1–14)/PTHrP(1–14) peptides andderivatives thereof. Compounds of the invention which includePTH(1–14)/PTHrP(1–14) peptides, fragments thereof, derivatives thereof,pharmaceutically acceptable salts thereof, and N- or C-derivativesthereof, are hereinafter collectively referred to as “compounds of SEQID NO:1 and derivatives thereof”.

In detail, the invention provides synthetic and/or recombinantbiologically active peptide derivatives of PTH(1–14) and PTHrP(1–14). Inone specific embodiment, this invention provides a biologically activepeptide at least 85% identical to a peptide consisting essentially ofthe formula:

(a) X₀₁ ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆(SEQ ID NO:1);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11,1–12, or1–13;

(c) pharmaceutically acceptable salts thereof; or

(d) N- or C-derivatives thereof,

wherein:

-   -   X₀₁ is Ser or Ala;    -   X₀₂ is Ile or His;    -   X₀₃ is Met, Leu or Nle;    -   X₀₄ is Asn or Asp;    -   X₀₅ is Leu or Lys; and    -   X₀₆ is His or Ser, provided that said peptide is not        PTHrP(1–14).

In accordance with yet a further aspect of the invention, this inventionalso provides pharmaceutical compositions comprising

(a) a biologically active peptide at least 85% identical to a peptideconsisting essentially of the formula: SerValSerGluIleGlnLeuMetHisAsnLeuGlyLysHis (SEQ ID NO:3);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) pharmaceutically acceptable salts thereof; or

(d) N- or C-derivatives thereof; and a pharmaceutically acceptablecarrier.

In accordance with yet a further aspect of the invention, this inventionalso provides pharmaceutical compositions comprising

(a) a biologically active peptide at least 85% identical to a peptideconsisting essentially of the formula: AlaValSerGluHisGlnLeuLeuHisAspLysGlyLysSer (SEQ ID NO:4);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) pharmaceutically acceptable salts thereof; or

(d) N- or C-derivatives thereof; and a pharmaceutically acceptablecarrier.

In accordance with yet a further aspect of the invention, this inventionprovides a nucleic acid molecule consisting essentially of apolynucleotide encoding a biologically active peptide which has an aminoacid sequence selected from the group consisting of:

(a) X₀₁ ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆(SEQ ID NO:1); or

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

wherein:

-   -   X₀₁ is Ser or Ala;    -   X₀₂ is Ile or His;    -   X₀₃ is Met, Leu or Nle;    -   X₀₄ is Asn or Asp;    -   X₀₅ is Leu or Lys; and    -   X₀₆ is His or Ser,        provided that said peptide is not PTHrP(1–14).

In accordance with yet a further aspect of the invention, this inventionprovides a recombinant DNA molecule comprising: (1) an expressioncontrol region, said region in operable linkage with (2) apolynucleotide sequence coding for a biologically active peptide,wherein said peptide is selected from the group consisting of:

(a) X₀₁ ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆(SEQ ID NO:1); or

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

wherein:

-   -   X₀₁ is Ser or Ala;    -   X₀₂ is Ile or His;    -   X₀₃ is Met, Leu or Nle;    -   X₀₄ is Asn or Asp;    -   X₀₅ is Leu or Lys; and    -   X₀₆ is His or Ser,        provided that said peptide is not PTHrP(1–14).

In accordance with yet a further aspect of the invention, this inventionprovides a method for treating mammalian conditions characterized bydecreases in bone mass, which method comprises administering to asubject in need thereof an effective bone mass-increasing amount of abiologically active peptide, wherein said peptide comprises an aminoacid sequence at least 85% identical to a member selected from the groupconsisting essentially of:

(a) X₀₁ ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆(SEQ ID NO:1);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) pharmaceutically acceptable salts thereof; or

(d) N- or C-derivatives thereof;

wherein:

-   -   X₀₁ is Ser or Ala;    -   X₀₂ is Ile or His;    -   X₀₃ is Met, Leu or Nle;    -   X₀₄ is Asn or Asp;    -   X₀₅ is Leu or Lys; and    -   X₀₆ is His or Ser,        provided that said peptide is not PTHrP(1–14); and a        pharmaceutically acceptable carrier.

In accordance with yet a further aspect of the invention, this inventionprovides a method for the treatment of a patient having need of abiologically active peptide comprising administering a therapeuticallyeffective amount of a peptide, wherein said peptide comprises an aminoacid sequence at least 85% identical to a member selected from the groupconsisting essentially of:

(a) a biologically active peptide consisting essentially of the formula:SerValSerGluIleGlnLeuMetHisAsnLeuGlyLysHis (SEQ ID NO:3);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) N- or C-derivatives thereof; or

(d) pharmaceutically acceptable salts thereof; and a pharmaceuticallyacceptable carrier.

In accordance with yet a further aspect of the invention, this inventionprovides a method for the treatment of a patient having need of abiologically active peptide comprising administering a therapeuticallyeffective amount of a peptide, wherein said peptide comprises an aminoacid sequence at least 85% identical to a member selected from the groupconsisting essentially of:

(a) a biologically active peptide consisting essentially of the formula:AlaValSerGluHisGlnLeuLeuHisAspLysGlyLysSer (SEQ ID NO:4);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) N- or C-derivatives thereof; or

(d) pharmaceutically acceptable salts thereof; and a pharmaceuticallyacceptable carrier.

In accordance with yet a further aspect of the invention, there isprovided a method for treating a medical disorder that results fromaltered or excessive action of the PTH-1/PTH-2 receptor, comprisingadministering to a patient a therapeutically effective amount of abiologically active peptide wherein said peptide comprises an amino acidsequence at least 85% identical to a member selected from the groupconsisting essentially of:

(a) X₀₁ ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆(SEQ ID NO:1);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) pharmaceutically acceptable salts thereof; or

(d) N- or C-derivatives thereof;

wherein:

-   -   X₀₁ is Ser or Ala;    -   X₀₂ is Ile or His;    -   X₀₃ is Met, Leu or Nle;    -   X₀₄ is Asn or Asp;    -   X₀₅ is Leu or Lys; and    -   X₀₆ is His or Ser,        provided said peptide is not PTHrP(1–14); and a pharmaceutically        acceptable carrier sufficient to inhibit activation of the        PTH-1/PTH-2 receptor of said patient.

In accordance with yet a further aspect of the invention, this inventionalso provides a method for determining rates of bone reformation, boneresorption and/or bone remodeling comprising administering to a patientan effective amount of a labeled peptide of SEQ ID NO: 1 or a derivativethereof and determining the uptake of said peptide into the bone of saidpatient. The peptide may be labeled with a label selected from the groupconsisting of: radiolabel, flourescent label, bioluminescent label, orchemiluminescent label. An example of a suitable radiolabel is ^(99m)Tc.

In accordance with yet a further aspect of the invention, any amino-acidsubstitutions at positions 1–9, and more particularly those amino acidsubstitutions at amino acid positions 10, 11, 12, 13, and/or 14, whichdo not destroy the biological activity of the PTH(1–14)/PTHrP(1–14)peptide analog to antagonize or agonize the PTH-1/PTH-2 receptor (asdetermined by assays known to the skilled artisan and discussed below),are also included within the scope of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. Bioactivity of amino-terminal and carboxy-terminal fragments ofPTH(1–34). Fragments of parathyroid hormone were synthesized by chemicalmethods and purified by reverse-phase HPLC. Peptides were tested for theability to stimulate cAMP accumulation in COS-7 cells expressing thecloned human PTH-1 receptor. PTH(1–34) was tested at a dose of 1 μM,other peptides were tested at 67 μM. Peptides were tested in duplicate(±s.e.m.) at a dose of 67 μM. The cAMP in control untreated cells isindicated by Bsl. Cells were treated for 30 minutes at 21° C.

FIG. 2. Alanine-scan of PTH(1–14). Shown are the bioactivities of 14different PTH(1–14) derivatives, each having a different amino acid ofthe native sequence (shown at bottom of figure) (SEQ ID NO:14) replacedby alanine. Peptides were chemically synthesized, purified and testedfor ability to stimulate cAMP formation in COS-7 cells expressing thecloned human PTH-1 receptor. Peptides were tested in duplicate (±s.e.m.)at a dose of 67 ÿM. As a control, untreated cells, indicated by basal,were measured. The PTH(1–14) containing alanine at position 1 was usedas the wild-type reference. Cells were stimulated for 30 minutes at 21°C.

FIG. 3. cAMP dose response curves of short amino-terminal PTH analogs inLLC-PK1 cells stably transfected with the human PTH-1 receptor (LLC-B7cells). LLC-B7 cells in 24 plates were treated with the indicatedpeptides for 60 mins at 21° C., and then intracellular cAMP levels weremeasured. All PTH peptides shown are based on the rat PTH sequence andare carboxy-terminally amidated. As can be seen, there is no gain inactivity when the PTH(1–14) peptide is extended to residue 15; andPTH(1–13) or shorter analogs exhibit only very weak activity.

FIG. 4. cAMP dose response curves of PTH(1–14) in LLC-B7 cells and inuntransfected LLC-PK1 cells. PTH(1–14) and PTH(1–34) control peptideswere tested as in FIG. 3. As can be seen, the response to PTH(1–14) inthese cells is completely dependent on the presence of the PTH-1receptor.

FIG. 5. Alanine-scan of PTH(1–14) in LLC-B7 cells. Each PTH(1–14) wastested in duplicate at a dose of 100 μM. LLC-B7 cells in 24 plates weretreated with the indicated peptides, for 60 mins at 21° C., and thenintracellular cAMP levels were measured.

FIG. 6. Specificity of PTH(1–14). The analog PTH(1–14) was tested inCOS-7 cells transfected with rat secretin receptor, which responds fullyto the control native secretin (1–27). PTH(1–14) does not stimulate cAMPin these cells. Thus, the response to PTH(1–14) is dependent on thepresence of the PTH-1 receptor.

FIG. 7. cAMP activity of [Ile5]PTHrP(1–14). LLC-B7 cells were treatedwith the indicated peptide ligand, each at 100 μM, and thenintracellular cAMP levels were measured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Definitions

In the description that follows, a number of terms used in recombinantDNA technology and peptide synthesis are utilized extensively. In orderto provide a clear and consistent understanding of the specification andclaims, including the scope to be given such terms, the followingdefinitions are provided.

Cloning vector: A plasmid or phage DNA or other DNA sequence which isable to replicate autonomously in a host cell, and which ischaracterized by one or a small number of restriction endonucleaserecognition sites at which such DNA sequences may be cut in adeterminable fashion without loss of an essential biological function ofthe vector, and into which a DNA fragment may be spliced in order tobring about its replication and cloning. The cloning vector may furthercontain a marker suitable for use in the identification of cellstransformed with the cloning vector. Markers, for example, providetetracycline resistance or ampicillin resistance.

Expression vector: A vector similar to a cloning vector but which iscapable of enhancing the expression of a gene which has been cloned intoit, after transformation into a host. The cloned gene is usually placedunder the control of (i. e., operably linked to) certain controlsequences such as promoter sequences. Promoter sequences may be eitherconstitutive or inducible.

Recombinant Host: According to the invention, a recombinant host may beany prokaryotic or eukaryotic host cell which contains the desiredcloned genes on an expression vector or cloning vector. This term isalso meant to include those prokaryotic or eukaryotic cells that havebeen genetically engineered to contain the desired gene(s) in thechromosome or genome of that organism. For examples of such hosts, seeSambrook et al., Molecular Cloning: A Laboratory Manual, Second Edition,Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1989).Preferred recombinant hosts are eukaryotic cells transformed with theDNA construct of the invention. More specifically, mammalian cells arepreferred.

Promoter: A DNA sequence generally described as the 5′ region of a gene,located proximal to the start codon. The transcription of an adjacentgene(s) is initiated at the promoter region. If a promoter is aninducible promoter, then the rate of transcription increases in responseto an inducing agent. In contrast, the rate of transcription is notregulated by an inducing agent if the promoter is a constitutivepromoter. Examples of promoters include the CMV promoter (InVitrogen,San Diego, Calif.), the SV40, MMTV, and hMTIIa promoters (U.S. Pat. No.5,457,034), the HSV-1 4/5 promoter (U.S. Pat. No. 5,501,979), and theearly intermediate HCMV promoter (WO92/17581). Also, tissue-specificenhancer elements may be employed. Additionally, such promoters mayinclude tissue and cell-specific promoters of an organism.

Polynucleotide: This term generally refers to any polyribonucleotide orpolydeoxribonucleotide, which may be unmodified RNA or DNA or modifiedRNA or DNA. “Polynucleotides” include, without limitation single- anddouble-stranded DNA, DNA that is a mixture of single- anddouble-stranded regions, single- and double-stranded RNA, and RNA thatis mixture of single- and double-stranded regions, hybrid moleculescomprising DNA and RNA that may be single-stranded or, more typically,double-stranded or a mixture of single- and double-stranded regions. Inaddition, “polynucleotide” refers to triple-stranded regions comprisingRNA or DNA or both RNA and DNA. The term polynucleotide also includesDNAs or RNAs containing one or more modified bases and DNAs or RNAs withbackbones modified for stability or for other reasons. “Modified” basesinclude, for example, tritylated bases and unusual bases such asinosine. A variety of modifications have been made to DNA and RNA; thus,“polynucleotide” embraces chemically, enzymatically or metabolicallymodified forms of polynucleotides as typically found in nature, as wellas the chemical forms of DNA and RNA characteristic of viruses andcells. “Polynucleotide” also embraces relatively short polynucleotides,often referred to as oligonucleotides.

Polypeptide: This term refers to any peptide or protein comprising twoor more amino acids joined to each other by peptide bonds or modifiedpeptide bonds, i.e., peptide isosteres. “Polypeptide” refers to bothshort chains, commonly referred to as peptides, oligopeptides oroligomers, and to longer chains, generally referred to as proteins.Polypeptides may contain amino acids other than the 20 gene-encodedamino acids. “Polypeptides” include amino acid sequences modified eitherby natural processes, such as post-translational processing, or bychemical modification techniques which are well known in the art. Suchmodifications are well described in basic texts and in more detailedmonographs, as well as in the research literature. Modifications canoccur anywhere in a polypeptide, including the peptide backbone, theamino acid side-chains and the amino or carboxyl termini. It will beappreciated that the same type of modification may be present in thesame or varying degrees at several sites in a given polypeptide. Also, agiven polypeptide may contain many types of modifications.

Polypeptides may be branched and they may be cyclic, with or withoutbranching. Cyclic, branched and branched cyclic polypeptides may resultfrom post-translation natural processes or may be made by syntheticmethods. Modifications include acetylation, acylation, ADP-ribosylation,amidation, covalent attachment of flavin, covalent attachment of a hememoiety, covalent attachment of a nucleotide or nucleotide derivative,covalent attachment of a lipid or lipid derivative, covalent attachmentof phosphotidylinositol, cross-linking, cyclization, disulfide bondformation, demethylation, formation of covalent cross-links, formationof cystine, formation of pyroglutamate, formylation,gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation,iodination, methylation, myristoylation, oxidation, proteolyticprocessing, phosphorylation, prenylation, racemization, selenoylation,sulfation, transfer-RNA mediated addition of amino acids to proteinssuch as arginylation, and ubiquitination. See, for instance,Proteins-Structure and Molecular Properties, 2nd Ed., T. E. Creighton,W. H. Freeman and Company, New York, 1993 and Wold, F.,Posttranslational Protein Modifications: Perspectives and Prospects,pgs. 1–12 in Posttranslational Covalent Modification of Proteins, B. C.Johnson, Ed., Academic Press, New York, 1983; Seifter et al., “Analysisfor protein modifications and nonprotein cofactors”, Methods in Enzymol.182:626–646 (1990) and Rattan et al., “Protein Synthesis:Posttranslational Modifications and Aging”, Ann NY Acad Sci 663:48–62(1992).

Homologous/Nonhomologous: Two nucleic acid molecules are considered tobe “homologous” if their nucleotide sequences share a similarity ofgreater than 40%, as determined by HASH-coding algorithms (Wilber, W. J.and Lipman, D. J., Proc. Natl. Acad. Sci. 80:726–730 (1983)). Twonucleic acid molecules are considered to be “nonhomologous” if theirnucleotide sequences share a similarity of less than 40%.

Isolated: A term meaning altered “by the hand of man” from the naturalstate. If an “isolated” composition or substance occurs in nature, ithas been changed or removed from its original environment, or both. Forexample, a polynucleotide or a polypeptide naturally present in a livinganimal is not “isolated,” but the same polynucleotide or polypeptideseparated from the coexisting materials of its natural state is“isolated”, as the term is employed herein. Thus, a polypeptide orpolynucleotide produced and/or contained within a recombinant host cellis considered isolated for purposes of the present invention. Alsointended as an “isolated polypeptide” or an “isolated polynucleotide”are polypeptides or polynucleotides that have been purified, partiallyor substantially, from a recombinant host cell or from a native source.For example, a recombinantly produced version of compounds of SEQ IDNO:1 and derivatives thereof can be substantially purified by theone-step method described in Smith and Johnson, Gene 67:31–40 (1988).

By “isolated” is meant that the DNA is free of the coding sequences ofthose genes that, in the naturally-occurring genome of the organism (ifany) from which the DNA of the invention is derived, immediately flankthe gene encoding the DNA of the invention. The isolated DNA may besingle-stranded or double-stranded, and may be genomic DNA, cDNA,recombinant hybrid DNA, or synthetic DNA. It may be identical to anative DNA sequence encoding compounds of SEQ ID NO:1 and derivativesthereof, or may differ from such sequence by the deletion, addition, orsubstitution of one or more nucleotides. Single-stranded DNAs of theinvention are generally at least 8 nucleotides long, (preferably atleast 18 nucleotides long, and more preferably at least 30 nucleotideslong) ranging up to full length of the DNA molecule encoding compoundsof SEQ ID NO:1 and derivatives thereof (i.e., 42 nucleotides); theypreferably are detectably labeled for use as hybridization probes, andmay be antisense.

High Stringency: By “high stringency” is meant, for example, conditionssuch as those described for the isolation of cDNA (also see CurrentProtocols in Molecular Biology, John Wiley & Sons, New York (1989),hereby incorporated by reference). The DNA of the invention may beincorporated into a vector [which may be provided as a purifiedpreparation (e.g., a vector separated from the mixture of vectors whichmake up a library)] containing a DNA sequence encoding a peptide of theinvention (e.g. compounds of SEQ ID NO:1 and derivatives thereof) and acell or essentially homogenous population of cells (e.g., prokaryoticcells, or eukaryotic cells such as mammalian cells) which contain thevector (or the isolated DNA described above).

Identity: This term refers to a measure of the identity of nucleotidesequences or amino acid sequences. In general, the sequences are alignedso that the highest order match is obtained. “Identity” per se has anart-recognized meaning and can be calculated using published techniques.(See, e.g.: Computational Molecular Biology, Lesk, A. M., ed., OxfordUniversity Press, New York, 1988; Biocomputing: Informatics and GenomeProjects, Smith, D. W., ed., Academic Press, New York, 1993; ComputerAnalysis of Sequence Data, Part I, Griffin, A. M., and Griffin, H. G.,eds., Humana Press, New Jersey, 1994; Sequence Analysis in MolecularBiology, von Heinje, G., Academic Press, 1987; and Sequence AnalysisPrimer, Gribskov, M. and Devereux, J., eds., M Stockton Press, New York,1991). While there exist a number of methods to measure identity betweentwo polynucleotide or polypeptide sequences, the term “identity” is wellknown to skilled artisans (Carillo, H. & Lipton, D., SIAM J Applied Math48:1073 (1988)). Methods commonly employed to determine identity orsimilarity between two sequences include, but are not limited to, thosedisclosed in Guide to Huge Computers, Martin J. Bishop, ed., AcademicPress, San Diego, 1994, and Carillo, H. & Lipton, D., SIAM J AppliedMath 48:1073 (1988). Methods to determine identity and similarity arecodified in computer programs. Preferred computer program methods todetermine identity and similarity between two sequences include, but arenot limited to, GCG program package (Devereux, J., et al., Nucleic AcidsResearch 12(i):387 (1984)), BLASTP, BLASTN, FASTA (Atschul, S. F., etal., J Molec Biol 215:403 (1990)).

Therefore, as used herein, the term “identity” represents a comparisonbetween a test and reference polypeptide. More specifically, referencetest polypeptide is defined as any polypeptide that is 85% or moreidentical to a reference polypeptide. As used herein, the term at least85% identical to refers to percent identities from 85 to 99.99 relativeto the reference polypeptides. Identity at a level of 85% or more isindicative of the fact that, assuming for exemplification purposes atest and reference polynucleotide length of 100 amino acids, that nomore than 15% (i.e., 15 out of 100) amino acids in the test polypeptidesdiffer from that of the reference polypeptides. Such differences may berepresented as point mutations randomly distributed over the entirelength of the amino acid sequence of the invention or they may beclustered in one or more locations of varying length up to the maximumallowable 2/14 amino acid difference (approximately 85% identity).Differences are defined as amino acid substitutions, or deletions.

Fragment: A “fragment” of a molecule such as a compound of SEQ ID NO: 1or derivative thereof is meant to refer to any polypeptide subset ofthese molecules.

Functional Derivative: The term “derivatives” is intended to include“variants,” the “derivatives,” or “chemical derivatives” of themolecule. A “variant” of a molecule such as a compound of SEQ ID NO: 1or derivative thereof is meant to refer to a molecule substantiallysimilar to either the entire molecule, or a fragment thereof. An“analog” of a molecule such as a compound of SEQ ID NO: 1 or derivativethereof is meant to refer to a non-natural molecule substantiallysimilar to either the SEQ ID NO: 1 molecules or fragments thereof.

A molecule is said to be “substantially similar” to another molecule ifthe sequence of amino acids in both molecules is substantially the same,and if both molecules possess a similar biological activity. Thus,provided that two molecules possess a similar activity, they areconsidered variants, derivatives, or analogs as that term is used hereineven if one of the molecules contains additional amino acid residues notfound in the other, or if the sequence of amino acid residues is notidentical.

As used herein, a molecule is said to be a “chemical derivative” ofanother molecule when it contains additional chemical moieties notnormally a part of the molecule. Such moieties may improve themolecule's solubility, absorption, biological half-life, etc. Themoieties may alternatively decrease the toxicity of the molecule,eliminate or attenuate any undesirable side effect of the molecule, etc.Examples of moieties capable of mediating such effects are disclosed inRemington's Pharmaceutical Sciences (1980) and will be apparent to thoseof ordinary skill in the art.

Biological Activity of the Protein: This expression refers to themetabolic or physiologic function of compounds of SEQ ID NO: 1 orderivatives thereof including similar activities or improved activitiesor those activities with decreased undesirable side-effects. Alsoincluded are antigenic and immunogenic activities of said compounds ofSEQ ID NO: 1 or derivatives thereof.

Fusion protein: By the term “fusion protein” is intended a fused proteincomprising compounds of SEQ ID NO: 1 or derivatives thereof, either withor without a “selective cleavage site” linked at its N-terminus, whichis in turn linked to an additional amino acid leader polypeptidesequence.

Selective cleavage site: The term “selective cleavage site” refers to anamino acid residue or residues which can be selectively cleaved witheither chemicals or enzymes in a predictable manner. A selective enzymecleavage site is an amino acid or a peptide sequence which is recognizedand hydrolyzed by a proteolytic enzyme. Examples of such sites include,without limitation, trypsin or chymotrypsin cleavage sites.

Leader Sequence: By the term “leader sequence” is intended apolynucleotide sequence linked to compounds of SEQ ID NO: 1, andexpressed in host cells as a fusion protein fused to the selectivecleavage site and compounds of SEQ ID NO: 1. The term “leaderpolypeptide” describes the expressed form of the “leader sequence” asobtained in the fusion protein.

The fusion protein, which is often insoluble and found in inclusionbodies when it is overexpressed, is purified from other bacterialprotein by methods well known in the art. In a preferred embodiment, theinsoluble fusion protein is centrifuged and washed after cell lysis, andresolubilized with guanidine-HCl. It can remain soluble after removal ofthe denaturant by dialysis. (For purification of refractile proteins,see Jones, U.S. Pat. No. 4,512,922; Olson, U.S. Pat. No. 4,518,526; andBuilder et al., U.S. Pat. Nos. 4,511,502 and 4,620,948).

The recombinantly produced compounds of SEQ ID NO: 1 or derivativesthereof can be purified to be substantially free of natural contaminantsfrom the solubilized fusion protein through the use of any of a varietyof methodologies. As used herein, a compound is said to be“substantially free of natural contaminants” if it has beensubstantially purified from materials with which it is found followingexpression in bacterial or eukaryotic host cells. Compounds of SEQ IDNO: 1 or derivatives thereof may be purified through application ofstandard chromatographic separation technology.

Alternatively, the peptide may be purified using immuno-affinitychromatography (Rotman, A. et al., Biochim. Biophys. Acta 641:114–121(1981); Sairam, M. R. J,. Chromatog 215:143–152 (1981); Nielsen, L. S.et al., Biochemistry 21:6410–6415 (1982); Vockley, J. et al., Biochem.J. 217:535–542 (1984); Paucha, E. et al., J. Virol. 51:670–681 (1984);and Chong, P. et al., J. Virol. Meth. 10:261–268 (1985)).

After partial or substantial purification, the fusion protein is treatedenzymatically with the enzyme corresponding to the cleavage site.Alternatively, the fusion protein in its more impure state, even inrefractile form, can be treated with the enzyme. If needed, theresulting mature compounds of SEQ ID NO: 1 or derivatives thereof, canbe further purified. Conditions for enzymatic treatment are known tothose of skill in the art.

Gene Therapy: A means of therapy directed to altering the normal patternof gene expression of an organism. Generally, a recombinantpolynucleotide is introduced into cells or tissues of the organism toeffect a change in gene expression.

Host Animal: Transgenic animals, all of whose germ and somatic cellscontain the DNA construct of the invention. Such transgenic animals arein general vertebrates. Preferred host animals are mammals such asnon-human primates, mice, sheep, pigs, cattle, goats, guinea pigs,rodents, e.g. rats, and the like. The term Host Animal also includesanimals in all stages of development, including embryonic and fetalstages.

I. Compounds of SEQ ID NO: 1 and Derivatives Thereof—Structural andFunctional Properties

We describe herein a novel “minimized” variant of PTH that retainsbioactivity, and is small enough to be deliverable by simplenon-injection methods. The new peptide corresponds to the 1–14 sequenceof native PTH or shorter variants thereof and thus has a molecularweight of less than 2,000 daltons. The present invention pertains to thenative PTH(1–14) peptide, the 1–14 sequence of PTH-related peptide(PTHrP), and peptide derivatives derived from these peptides byalteration in amino acid composition or amino acid chain length.

The primary amino acid sequence of the native PTH(1–14) peptide(N-terminus to C-terminus) is SerValSerGluIleGlnLeuMetHisAsnLeuGlyLysHis(SEQ ID NO: 3), whereas the primary amino acid sequence of the nativePTHrP(1–14) peptide (N-terminus to C-terminus) isAlaValSerGluHisGlnLeuLeu HisAspLysGlyLysSer (SEQ ID NO: 4). Accordingly,the peptide sequence in common between Sequence ID NOs: 3 and 4 consistsof the following generic formula:X₀₁ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆ (SEQ ID NO:1)wherein:

X₀₁ is Ser or Ala;

X₀₂ is Ile or His;

X₀₃ is Met, Leu, or Nle;

X₀₄ is Asn or Asp;

X₀₅ is Leu or Lys; and

X₀₆ is His or Ser,

provided that said peptide is not PTHrP(1–14).

Thus, based upon the above noted generic formula, this inventionprovides biologically active compounds of SEQ ID NO: 1 and derivativesthereof. In one specific embodiment, this invention provides abiologically active peptide at least 85% identical to a peptideconsisting essentially of the formula:

(a) X₀₁ValSerGluX₀₂GlnLueX₀₃HisX₀₄X₅GlyLysX₆(SEQ ID NO: 1);

(b) fragments thereof containing amino acids 1–9, 1–10, 1–11, 1–12, or1–13;

(c) pharmaceutically acceptable salts thereof; or

(d) N- or C-derivatives thereof;

wherein:

X₀₁ is Ser or Ala;

X₀₂ is Ile or His;

X₀₃ is Met, Leu or Nle;

X₀₄ is Asn or Asp;

X₀₅ is Leu or Lys; and

X₀₆ is His or Ser,

provided that said peptide is not PTHrP(1–14).

As protein products, compounds of SEQ ID NO: 1 or derivatives thereof ofthe present invention are amenable to production by the technique ofsolution- or solid-phase peptide synthesis. The solid phase peptidesynthesis technique, in particular, has been successfully applied in theproduction of human PTH and can be used for the production of compoundsof SEQ ID NO: 1 or derivatives thereof of the present invention (forguidance, see Kimura et al., supra, and see Fairwell et al., Biochem.22:2691 (1983)). Success with producing human PTH on a relatively largescale has been reported by Goud et al., in J. Bone Min. Res. 6(8):781(1991), incorporated herein by reference. The synthetic peptidesynthesis approach generally entails the use of automated synthesizersand appropriate resin as solid phase, to which is attached theC-terminal amino acid of the desired compounds of SEQ ID NO: 1 orderivatives thereof. Extension of the peptide in the N-terminaldirection is then achieved by successively coupling a suitably protectedform of the next desired amino acid, using either FMOC- or BOC-basedchemical protocols typically, until synthesis is complete. Protectinggroups are then cleaved from the peptide, usually simultaneously withcleavage of peptide from the resin, and the peptide is then isolated andpurified using conventional techniques, such as by reversed phase HPLCusing acetonitrile as solvent and trifluoroacetic acid as ion-pairingagent. Such procedures are generally described in numerous publicationsand reference may be made, for example, to Stewart and Young, “SolidPhase Peptide Synthesis,” 2nd Edition, Pierce Chemical Company,Rockford, Ill. (1984). It will be appreciated that the peptide synthesisapproach is required for production of SEQ ID NO: 1 and derivativesthereof variants which incorporate amino acids that are not geneticallyencoded.

In a further aspect of the invention, any amino-acid substitutions atpositions 1–9, and more particularly those amino acid substitutions atamino acid positions 10, 11, 12, 13, and/or 14, which do not destroy thebiological activity of the PTH/PTHrP peptide analog to antagonize oragonize the PTH-1/PTH-2 receptor (as determined by assays known to theskilled artisan and discussed below), are also included within the scopeof the present invention.

The synthetic analog of bovine PTH, PTH(3–34) has been recognized as apotent PTH antagonist in vitro. Variants of PTH lacking N-terminal aminoacids 1–2 and 1–7, were shown to be devoid of agonist activity andcapable of antagonist activity (Born, W. et al., Endocrinol.23:1848–1853 (1988)). Preferred potential antagonist variants of SEQ IDNO: 1 of this invention are variants truncated at the N-terminus.

When a variant is truncated by one amino acid at the N-terminus, it istermed PTH or PTHrP(2–14), in that it lacks amino acid residue #1 butcontains amino acid residues #2–14. When a variant is truncated by oneamino acid at the C-terminus, it is termed PTH or PTHrP(1–13), in thatit lacks amino acid residue #14 but contains amino acid residues #1–13.

In accordance with another aspect of the present invention, substituentsmay be attached to the free amine of the N-terminal amino acid ofcompounds of SEQ ID NO: 1 or derivatives thereof by standard methodsknown in the art. For example, alkyl groups, e.g., C₁₋₁₂alkyl, may beattached using reductive alkylation. Hydroxyalkyl groups, e.g.C₁₋₁₂hydroxyalkyl, may also be attached using reductive alkylationwherein the free hydroxy group is protected with a t-butyl ester. Acylgroups, e.g., COE₁, may be attached by coupling the free acid, e.g.,E₁COOH, to the free amino of the N-terminal amino acid. Alsocontemplated within the scope of this invention are those compounds ofSEQ ID NO:1 and derivatives thereof that alter secondary or tertiarystructure, or stability of compounds of SEQ ID NO: 1 or derivativesthereof which still retain biological activity. Such derivatives mightbe achieved through lactam cyclization, disulfide bonds, or other meansknown to a person of ordinary skill in the art.

Among the preferred embodiments are those compounds which may serve asagonists of the PTH-1/PTH-2 receptor. In particular, preferredembodiments are those compounds where X₀₁ is Ala; X₀₂ is Ile; X₀₃ isMet; X₀₄ is Asn; X₀₅ is Leu; and X₀₆ is His. The amino acid sequence ofthis preferred embodiment is thusAlaValSerGluIleGlnLeuMetHisAsnLeuGlyLysHis (SEQ ID NO: 5) or derivativesthereof.

Another set of the preferred embodiments are those compounds having afive amino acid deletion at the carboxy terminus of SEQ ID NO: 1 whereX₀₁ is Ala; X₀₂ is Ile; and X₀₃ is Met. The amino acid sequence of thispreferred embodiment is thus AlaValSerGluIleGlInLeuMetHis (SEQ ID NO: 6)or derivatives thereof.

Another set of preferred embodiments are those compounds where X₀₁ isAla; X₀₂ is Ile; X₀₃ is Leu; X₀₄ is Asp; X₀₅ is Lys; and X₀₆ is Ser. Theamino acid sequence of this preferred embodiment is thusAlaValSerGluIleGlnLeuLeuHisAsp LysGlyLysSer (SEQ ID NO: 2) orderivatives thereof.

Another set of preferred embodiments are those compounds having a fiveamino acid deletion at the carboxy terminus of SEQ ID NO: 1 where X₀₁ isAla; X₀₂ is Ile; and X₀₃ is Leu. The amino acid sequence of thispreferred embodiment is thus AlaValSerGluIleGlnLeuLeuHis (SEQ ID NO: 7)or derivatives thereof.

Another set of preferred embodiments are those compounds having a fiveamino acid deletion at the carboxy terminus of SEQ ID NO: 1 where X₀₁ isAla; X₀₂ is His; and X₀₃ is Leu. The amino acid sequence of thispreferred embodiment is thus AlaValSerGluHisGlnLeuLeuHis (SEQ ID NO: 8)or derivatives thereof.

Another set of the preferred embodiments are those compounds where X₀ isSer; X₀₂ is His; X₀₃ is Leu; X₀₄ is Asp; X₀₅ is Lys; and X₀₆ is Ser. Theamino acid sequence of this preferred embodiment is thusSerValSerGluHisGlnLeu LeuHisAspLysGlyLysSer (SEQ ID NO: 9) orderivatives thereof.

Another set of the preferred embodiments are those compounds having afive amino acid deletion at the carboxy terminus of SEQ ID NO: 1 whereX₀ l is Ser; X₀₂ is His; and X₀₃ is Leu. The amino acid sequence of thispreferred embodiment is thus SerValSerGluHisGlnLeuLeuHis (SEQ ID NO: 10)or derivatives thereof.

Among the preferred embodiments are those compounds which may serve asantagonists of the PTH-1/PTH-2 receptor. In particular, preferredembodiments are those compounds having a single amino acid deletion atthe amino terminus of SEQ ID NO: 1 where X₀₂ is Ile; X₀₃ is Met; X₀₄ isAsn; X₀₅ is Leu; and X₀₆ is His. The amino acid sequence of thispreferred embodiment is thus ValSerGlulIeGlnLeuMetHisAsnLeuGlyLysHis(SEQ ID NO: 11) or derivatives thereof.

Yet another set of preferred antagonist embodiments are those compoundshaving a single amino acid deletion at the amino terminus of SEQ ID NO:1 where X₀₂ is Ile; X₀₃ is Leu; X₀₄ is Asp; X₀₅ is Lys; and X₀₆ is Ser.The amino acid sequence of this preferred embodiment is thusValSerGluIleGlnLeuLeuHisAspLys GlyLysSer (SEQ ID NO: 12) or derivativesthereof.

Yet another set of preferred antagonist embodiments are those compoundshaving a single amino acid deletion at the amino terminus of SEQ ID NO:1 where X₀₂ is His; X₀₃ is Leu; X₀₄ is Asp; X₀₅ is Lys; and X₀₆ is Ser.The amino acid sequence of this preferred embodiment is thusValSerGluHisGlnLeuLeuHisAsp LysGlyLysSer (SEQ ID NO: 13) or derivativesthereof.

II. Biological Characterization of Compounds of SEQ ID NO:1 andDerivatives Thereof

Functional characterization of the biological properties of thecompounds of SEQ ID NO:1 and derivatives thereof was performed bybioassays that measure ligand-stimulated cAMP accumulation.

A. Stimulation of Cyclic AMP Accumulation by Compounds of SEQ ID NO: 1or Derivatives Thereof

Intracellular cAMP accumulation was measured as described previously(Abou-Samra et al., J. Biol. Chem. 262:1129, 1986). Cells in 24-wellplates were rinsed with culture medium containing 0.1% BSA and 2 mMIBMX. The cells were then incubated with compounds of SEQ ID NO: 1 orderivatives thereof for 60 min. at 21° C. The supernatant was removedand the cells immediately frozen by placing the whole plate in dry icepowder. Intracellular cAMP was extracted by thawing the cells in 1 ml of50 mM HCl and analyzed by a specific radioimmunoassay using an anti-cAMPantibody (e.g., Sigma, St. Louis, Mo.). A cAMP analog(2′-O-monosuccinyl-adenosine3′:5′-cyclic monophosphate tyrosyl methylester, obtained from Sigma) which was used a tracer for cAMP wasiodinated by the chloramine T method. Free iodine was removed byadsorbing the iodinated cAMP analog onto a C18 Sep-pak cartridge(Waters, Milford, Mass.). After washing with dH₂O, the iodinated cAMPanalog was eluted from the Sep-pak Cartridge with 40% acetonitrille(ACN) and 0.1% trifluoroacetic acid (TFA). The iodinated cAMP analog waslyophilized, reconstituted in 1 ml 0.1% TFA, and injected into a C18reverse phase HPLC column (Waters). The column was equilibrated with 10%ACN in 0.1% TFA, and eluted with gradient of 10–30% ACN in 0.1% TFA.This allows separation of the mono-iodinated cAMP analog from thenon-iodinated cAMP analog. The tracer is stable for up to 4 months whenstored at −20° C. The standard used for the assay, adenosine3′:5′-cyclic monophosphate, was purchased from Sigma. Samples (1–10 82 Iof HCl extracts) or standards (0.04–100 fmol/tube) were diluted in 50 mMNa-acetate (pH 5.5), and acetylated with 10 μl of mixture oftriethylamine and acetic anhydride (2:1 vol:vol). After acetylation,cAMP antiserum (100 μl) was added from a stock solution (1:4000) made inPBS (pH 7.4), 5 mM EDTA and 1% normal rabbit serum. The tracer wasdiluted in PBS (pH 7.4) with 0.1% BSA, and added (20,000 cpm/tube). Theassay was incubated at 4° C. overnight. The bound tracer wasprecipitated by adding 100 μl of goat anti-rabbit antiserum (1:20 inPBS) and 1 ml of 7% polyethyleneglycol (MW 5000–6000), centrifuging at2000 rpm for 30 min. at 4° C. The supernatant was removed and the boundradioactivity was counted in a gamma-counter (Micromedic). To computethe cAMP data, logit calculations were performed in Excel spreadsheets.Typically, the assay sensitivity is 0.1 fmol/tube, and the standardconcentration that displaces 50% of tracer is 5 fmol/tube.

B. Binding of Compounds of SEQ ID NO: 1 or Derivatives Thereof to ClonedReceptors Expressed on COS Cells

In addition to the cAMP accumulation assay described below, compounds ofSEQ ID NO: 1 or derivatives thereof may also be iodinated and used in aradioreceptor-based assay in transiently transfected COS cells. COS-7cells are grown in 15 cm plates in DMEM, 10% heat-inactivated FBS, 10mg/L gentamycin until 80–90% confluent. Twenty-four hours aftertransfection by the DEAE/Dextran method (Sambrook et al., supra), with1–2 μg of plasmid DNA, the cells are trypsinized and replated inmultiwell plastic dishes (16 or 35 mm diameter, Costar, Cambridge,Mass.) at a cell concentration of 5×10⁴ cells/cm². Cell number increasedonly slightly after transfection. After continuing culture for another48 h, radioreceptor assays are performed. The culture medium is replacedwith buffer containing 50 mM Tris-HCL (pH 7.7), 100 mM NaCl, 2 mM CaCl₂,5 mM KCL, 0.5% heat-inactivated fetal bovine serum (GIBCO), and 5%heat-inactivated horse serum (KC Biological Inc., Lenexa, Kans.)immediately before studies are initiated. Unless otherwise indicated,studies are conducted with cells incubated in this buffer at 15° C. for4 h with 4×10⁵ cpm/ml (9.6×10⁻¹¹ M) of ¹²⁵I-labeled [Ala¹]PTH(1–14)amide or ¹²⁵I-labeled [Nle⁸]PTH(1–14).

III. Vectors, Host Cells, and Recombinant Expression

The present invention also relates to vectors that comprise apolynucleotide of the present invention, and host cells which aregenetically engineered with vectors of the invention and the productionof polypeptides of the invention by recombinant techniques. Cell-freetranslation systems can also be employed to produce such proteins usingRNAs derived from the DNA constructs of present invention.

For recombinant production, host cells can be genetically engineered toincorporate expression systems or portions thereof for polynucleotidesof the present invention. Introduction of polynucleotides into hostcells can be effected by methods described in many standard laboratorymanuals, such as Davis et al., Basic Methods in Molecular Biology (1986)and Sambrook et al., Molecular Cloning: A Laboratory Manual, 2nd Ed.,Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989)such as calcium phosphate transfection, DEAE-dextran mediatedtransfection, transvection, microinjection, cationic lipid-mediatedtransfection, electroporation, transduction, scrape loading, ballisticintroduction or infection.

Representative examples of appropriate hosts include bacterial cells,such as streptococci, staphylococci, E. coli, Streptomyces and Bacillussubtilis cells; fungal cells, such as yeast cells and Aspergillus cells;insect cells such as Drosophila S2 and Spodoptera Sf9 cells; animalcells such as CHO, COS, HeLa, C127, 3T3, BHK, 293 and Bowes melanomacells; and plant cells.

A great variety of expression systems can be used. Such systems include,among others, chromosomal, episomal and virus-derived systems, e.g.,vectors derived from bacterial plasmids, from bacteriophage, fromtransposons, from yeast episomes, from insertion elements, from yeastchromosomal elements, from viruses such as baculoviruses, papovaviruses, such as SV40, vaccinia viruses, adenoviruses, fowl pox viruses,pseudorabies viruses, and retroviruses, and vectors derived fromcombinations thereof, such as those derived from plasmid andbacteriophage genetic elements, such as cosmids and phagemids. Theexpression systems may contain control regions that regulate as well asengender expression. Generally, any system or vector suitable tomaintain, propagate or express polynucleotides to produce a polypeptidein a host may be used. The appropriate nucleotide sequence may beinserted into an expression system by any of a variety of well-known androutine techniques, such as, for example, those set forth in Sambrook etal., Molecular Cloning: A Laboratory Manual (supra).

RNA vectors may also be utilized for the expression of the nucleic acidsencoding compounds of SEQ ID NO: 1 or derivatives thereof disclosed inthis invention. These vectors are based on positive or negative strandRNA viruses that naturally replicate in a wide variety of eukaryoticcells (Bredenbeek, P. J. & Rice, C. M., Virology 3: 297–310, 1992).Unlike retroviruses, these viruses lack an intermediate DNA life-cyclephase, existing entirely in RNA form. For example, alpha viruses areused as expression vectors for foreign proteins because they can beutilized in a broad range of host cells and provide a high level ofexpression; examples of viruses of this type include the Sindbis virusand Semliki Forest virus (Schlesinger, S., TIBTECH 11:18–22, 1993;Frolov, I., et al., Proc. Natl. Acad. Sci. (USA) 93: 11371–11377, 1996).As exemplified by Invitrogen's Sinbis expression system, theinvestigator may conveniently maintain the recombinant molecule in DNAform (pSinrep5 plasmid) in the laboratory, but propagation in RNA formis feasible as well. In the host cell used for expression, the vectorcontaining the gene of interest exists completely in RNA form and may becontinuously propagated in that state if desired.

For secretion of the translated protein into the lumen of theendoplasmic reticulum, into the periplasmic space or into theextracellular environment appropriate secretion signals may beincorporated into the desired polypeptide. These signals may beendogenous to the polypeptide or they may be heterologous signals.

The expression of a DNA sequence requires that the DNA sequence be“operably linked” to DNA sequences which contain transcriptional andtranslational regulatory information. An operable linkage is a linkagein which the control or regulatory DNA sequences and the DNA sequencesought to be expressed are connected in such a way as to permit geneexpression. The precise nature of the “control regions” needed for geneexpression may vary from organism to organism, but shall in generalinclude a promoter region which, in prokaryotic cells, contains both thepromoter (which directs the initiation of RNA transcription) as well asDNA sequences which, when transcribed into RNA, will signal theinitiation of protein synthesis. Regulatory regions in eukaryotic cellswill in general include a promoter region sufficient to direct theinitiation of RNA synthesis.

Two DNA sequences are said to be operably linked if the nature of thelinkage between the two DNA sequences does not (1) result in theintroduction of a frameshift mutation, (2) interfere with the ability ofthe promoter region sequence to direct the transcription of the fusionprotein-encoding sequence or (3) interfere with the ability of thefusion protein-encoding sequence to be transcribed by the promoterregion sequence. Thus, a promoter region would be operably linked to aDNA sequence if the promoter were capable of transcribing that DNAsequence.

The joining of various DNA fragments, to produce the expression vectorsof this invention is performed in accordance with conventionaltechniques, employing blunt-ended or staggered-ended termini forligation, restriction enzyme digestion to provide appropriate termini,filling in of cohesive ends as appropriate, alkali and phosphatasetreatment to avoid undesirable joining, and ligation with appropriateligates. In the case of a fusion protein, the genetic construct encodesan inducible promoter which is operably linked to the 5′ gene sequenceof the fusion protein to allow efficient expression of the fusionprotein.

To express compounds of SEQ ID NO: 1 or a derivative thereof in aprokaryotic cell (such as, for example, E. coli, B. subtilis,Pseudomonas, Streptomyces, etc.), it is necessary to operably link theSEQ ID NO: 1-encoding DNA sequence to a functional prokaryotic promoter.Such promoters may be either constitutive or, more preferably,regulatable (i.e., inducible or derepressible). Examples of constitutivepromoters include the int promoter of bacteriophage λ, the bla promoterof the β-lactamase gene of pBR322, and the CAT promoter of thechloramphenicol acetyl transferase gene of pBR325, etc. Examples ofinducible prokaryotic promoters include the major right and leftpromoters of bacteriophage λ, (PL and PR), the trp, recA. lacZ. lacI.and gal promoters of E. coli, the α-amylase (Ulmanen, I. et al., J.Bacteriol. 162:176–182 (1985)), and the σ-28-specific promoters of B.subtilis (Gilman, M. Z. et al., Gene 32:11–20 (1984)), the promoters ofthe bacteriophages of Bacillius (Gryczan, T. J., In: The MolecularBiology of the Bacilli, Academic Press, Inc., NY (1982)), andStreptomyces promoters (Ward, J. M. et al., Mol. Gen. Genet. 203:468–478(1986)). Prokaryotic promoters are reviewed by Glick, B. R., J. Ind.Microbiol. 1:277–282 (1987); Cenatiempo, Y., Biochimie 68:505–516(1986)); and Gottesman, S., Ann. Rev. Genet. 18:415–442 (1984)).

The preferred prokaryotic promoter for this invention is the E. coli trppromoter, which is inducible with indole acrylic acid.

If expression is desired in a eukaryotic cell, such as yeast, fungi,mammalian cells, or plant cells, then it is necessary to employ apromoter capable of directing transcription in such a eukaryotic host.Preferred eukaryotic promoters include the promoter of the mousemetallothionein I gene (Hamer, D. et al., J. Mol. Appl. Gen. 1:273–288(1982)); the TK promoter of Herpes virus (McKnight, S., Cell 31:355–365(1982)); the SV40 early promoter (Benoist, C., et al., Nature (London)290:304–310 (1981)); and the yeast gal4 gene promoter (Johnston, S. A.,et al., Proc. Natl. Acad. Sci. (USA) 79:6971–6975 (1982); Silver, P. A.,et al., Proc. Natl. Acad. Sci. (USA) 81:5951–5955 (1984)).

Preferably, the introduced gene sequence will be incorporated into aplasmid or viral vector capable of autonomous replication in therecipient host. Any of a wide variety of vectors may employed for thispurpose. Factors of importance in selecting a particular plasmid orviral vector include: the ease with which recipient cells that containthe vector may be recognized and selected from those recipient cellswhich do not contain the vector; the number of copies of the vectorwhich are desired in a particular host; and whether it is desirable tobe able to “shuttle” the vector between host cells of different species.

Preferred prokaryotic vectors include plasmids such as those capable ofreplication in E. coli (such as, for example, pBR322, ColE1, pSC101,pACYC 184, πVX. Such plasmids are, for example, disclosed by Maniatis,T., et al., In: Molecular Cloning, A Laboratory Manual, Cold SpringHarbor Press, Cold Spring Harbor, N.Y. (1982)). Preferred plasmidexpression vectors include the pGFP-1 plasmid described in Gardella etal., J. Biol. Chem 265:15854–15859 (1989), or a modified plasmid basedupon one of the pET vectors described by Studier and Dunn, Methods inEnzymology 185: 60–89 (1990). Bacillus plasmids include pC194, pC221,pT127, etc. Such plasmids are disclosed by Gryczan, T. In: The MolecularBiology of the Bacilli, Academic Press, NY pp. 307–329 (1982). SuitableStreptomyces plasmids include pIJIOI (Kendall, K. J. et al., J.Bacteriol. 169:4177–4183 (1987)), and streptomyces bacteriophages suchas φC31 (Chater, K. F. et al., In: Sixth International Symposium onActinomycetales Biology, Akademiai Kaido, Budapest, Hungary, pp.45–54(1986)). Pseudomonas plasmids are reviewed by John, J. F. et al., Rev.Infect. Dis. 8:693–704 (1986)), and Izaki, K., Jon. J. Bacteriol.33:729–742 (1978)).

Preferred eukaryotic expression vectors include, without limitation,BPV, vaccinia, 2-micron circle etc. Such expression vectors are wellknown in the art (Botstein, D., et al., Miami Wntr. Symp. 19:265–274(1982); Broach, J. R., In: The Molecular Biology of the YeastSaccharomyces: Life Cycle and Inheritance, Cold Spring HarborLaboratory, Cold Spring Harbor, N.Y. pp. 445–470 (1981); Broach, J. R.,Cell 28:203–204 (1982); Bollon, D. P., et al., J. Clin. Hematol. Oncol.10:39–48 (1980); Maniatis, T., In: Cell Biology. A ComprehensiveTreatise, Vol. 3, Gene Expression, Academic Press, NY, pp. 563–608(1980)).

In addition to microorganisms, cultures of cells derived frommulticellular organisms may also be used as hosts. In principle, anysuch cell culture is workable, whether from vertebrate or invertebratecellular sources. Interest, however, has been greater with cells fromvertebrate sources. Examples of useful vertebrate host cell lines areVERO and HeLa cells, Chinese hamster ovary (CHO) cell lines, WI138, BHK,COS-7, and MDCK cell lines. Expression vectors for such cells ordinarilyinclude (if necessary) an origin of replication, a promoter located infront of or upstream to the gene to be expressed, along with anynecessary ribosome binding sites, RNA splice sites, polyadenylationsite, and transcriptional terminator sequences.

For use in mammalian cells, the control functions on the expressionvectors are often provided by viral material. For example, commonly usedpromoters are derived from polyoma, Adenovirus 2, Simian Virus 40 (SV40)and cytomegalovirus. The early and late promoters of SV40 virus areparticularly useful because both are obtained easily from the virus as afragment which also contains the SV40 vial origin of replication (Fierset al., Nature 273:113 (1978)).

An origin of replication may be provided either by construction of thevector to include an exogenous origin, such as may be derived from SV40or other viral (e.g. Polyoma, Adeno, VSV, BPV) source or may be providedby the host cell chromosomal replication mechanism. If the vector isintegrated into the host cell chromosome, the latter is oftensufficient.

If cells without formidable cell membrane barriers are used as hostcells, transfection is carried out by the calcium phosphateprecipitation method as described by Graham and Van der Erb, Virology52:546 (1978). However, other methods for introducing DNA into cells,such as by nuclear injection or by protoplast fusion may also be used.In the case of gene therapy, the direct naked plasmid or viral DNAinjection method, with or without transfection-facilitating agents suchas, without limitation, liposomes, provides an alternative approach tothe current methods of in vivo or in vitro transfection of mammaliancells. If prokaryotic cells or cells which contain substantial cell wallconstructions are used, the preferred method of transfection is calciumtreatment, using calcium chloride as described in Cohen et al., Proc.Natl. Acad. Sci. USA 69:2110 (1972).

IV. Utility and Administration of Compounds of SEQ ID NO:1 orDerivatives Thereof

Compounds of SEQ ID NO: 1 or derivatives thereof of this invention areuseful for the prevention and treatment of a variety of mammalianconditions manifested by loss of bone mass. In particular, the compoundsof this invention are indicated for the prophylaxis and therapeutictreatment of osteoporosis and osteopenia in humans. Furthermore, thecompounds of this invention are indicated for the prophylaxis andtherapeutic treatment of other bone diseases. The compounds of thisinvention are indicated for the prophylaxis and therapeutic treatment ofhypoparathyroidism. Finally, the compounds of this invention areindicated for use as agonists for fracture repair and as antagonists forhypercalcemia.

In general, compounds of SEQ ID NO: 1 or derivatives thereof of thisinvention, or salts thereof, are administered in amounts between about0.01 and 1 μg/kg body weight per day, preferably from about 0.07 toabout 0.2 μg/kg body weight per day. For a 50 kg human female subject,the daily dose of biologically active compounds of SEQ ID NO: 1 orderivatives thereof is from about 0.5 to about 50 μgs, preferably fromabout 3.5 to about 10 μgs. In other mammals, such as horses, dogs, andcattle, higher doses may be required. This dosage may be delivered in aconventional pharmaceutical composition by a single administration, bymultiple applications, or via controlled release, as needed to achievethe most effective results, preferably one or more times daily byinjection. For example, this dosage may be delivered in a conventionalpharmaceutical composition by nasal insufflation.

The selection of the exact dose and composition and the most appropriatedelivery regimen will be influenced by, inter alia, the pharmacologicalproperties of the selected compounds of SEQ ID NO: 1 or derivativesthereof, the nature and severity of the condition being treated, and thephysical condition and mental acuity of the recipient.

Representative preferred delivery regimens include, without limitation,oral, parenteral (including subcutaneous, transcutaneous, intramuscularand intravenous), rectal, buccal (including sublingual), transdermal,and intranasal insufflation.

Pharmaceutically acceptable salts retain the desired biological activityof the compounds of SEQ ID NO: 1 or derivatives thereof without toxicside effects. Examples of such salts are (a) acid addition salts formedwith inorganic acids, for example hydrochloric acid, hydrobromic acid,sulfuric acid, phosphoric acid, nitric acid and the like; and saltsformed with organic acids such as, for example, acetic acid, oxalicacid, tartaric acid, succinic acid, maleic acid, fumaric acid, gluconicacid, citric acid, malic acid, ascorbic acid, benzoic acid, tannic acid,pamoic acid, alginic acid, polyglutamic acid, naphthalenesulfonic acids,naphthalene disulfonic acids, polygalacturonic acid and the like; (b)base addition salts formed with polyvalent metal cations such as zinc,calcium, bismuth, barium, magnesium, aluminum, copper, cobalt, nickel,cadmium, and the like; or with an organic cation formed fromN,N′-dibenzylethylenediamine or ethylenediamine; or (c) combinations of(a) and (b), e.g., a zinc tannate salt and the like.

A further aspect of the present invention relates to pharmaceuticalcompositions comprising as an active ingredient compounds of SEQ ID NO:1 or derivatives thereof of the present invention, or pharmaceuticallyacceptable salt thereof, in admixture with a pharmaceuticallyacceptable, non-toxic carrier. As mentioned above, such compositions maybe prepared for parenteral (subcutaneous, transcutaneous, intramuscularor intravenous) administration, particularly in the form of liquidsolutions or suspensions; for oral or buccal administration,particularly in the form of tablets or capsules; for rectal, transdermaladministration; and for intranasal administration, particularly in theform of powders, nasal drops or aerosols.

The compositions may conveniently be administered in unit dosage formand may be prepared by any of the methods well-known in thepharmaceutical art, for example as described in Remington'sPharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa.,(1985), incorporated herein by reference. Formulations for parenteraladministration may contain as excipients sterile water or saline,alkylene glycols such as propylene glycol, polyalkylene glycols such aspolyethylene glycol, oils of vegetable origin, hydrogenated naphthalenesand the like. For oral administration, the formulation can be enhancedby the addition of bile salts or acylcarnitines. Formulations for nasaladministration may be solid and may contain excipients, for example,lactose or dextran, or may be aqueous or oily solutions for use in theform of nasal drops or metered spray. For buccal administration typicalexcipients include sugars, calcium stearate, magnesium stearate,pregelatinated starch, and the like.

When formulated for the most preferred route of administration, nasaladministration, the absorption across the nasal mucous membrane may beenhanced by surfactant acids, such as for example, glycocholic acid,cholic acid, taurocholic acid, ethocholic acid, deoxycholic acid,chenodeoxycholic acid, dehydrocholic acid, glycodeoxycholic acid,cyclodextrins and the like in an amount in the range between about 0.2and 15 weight percent, preferably between about 0.5 and 4 weightpercent, most preferably about 2 weight percent.

Delivery of the compounds of the present invention to the subject overprolonged periods of time, for example, for periods of one week to oneyear, may be accomplished by a single administration of a controlledrelease system containing sufficient active ingredient for the desiredrelease period. Various controlled release systems, such as monolithicor reservoir-type microcapsules, depot implants, osmotic pumps,vesicles, micelles, liposomes, transdermal patches, iontophoreticdevices and alternative injectable dosage forms may be utilized for thispurpose. Localization at the site to which delivery of the activeingredient is desired is an additional feature of some controlledrelease devices, which may prove beneficial in the treatment of certaindisorders.

One form of controlled release formulation contains the polypeptide orits salt dispersed or encapsulated in a slowly degrading, non-toxic,non-antigenic polymer such as copoly(lactic/glycolic) acid, as describedin the pioneering work of Kent, Lewis, Sanders, and Tice, U.S. Pat. No.4,675,189, incorporated by reference herein. The compounds or,preferably, their relatively insoluble salts, may also be formulated incholesterol or other lipid matrix pellets, or silastomer matriximplants. Additional slow release, depot implant or injectableformulations will be apparent to the skilled artisan. See, for example,Sustained and Controlled Release Drug Delivery Systems, J. R. Robinsoned., Marcel Dekker, Inc., New York, 1978, and R. W. Baker, ControlledRelease of Biologically Active Agents, John Wiley & Sons, New York,1987, incorporated by reference herein.

Like PTH, the PTH variants may be administered in combination with otheragents useful in treating a given clinical condition. When treatingosteoporosis and other bone-related disorders for example, the PTHvariants may be administered in conjunction with a dietary calciumsupplement or with a vitamin D analog (see U.S. Pat. No. 4,698,328).Alternatively, the PTH variant may be administered, preferably using acyclic therapeutic regimen, in combination with bisphosphonates, asdescribed for example in U.S. Pat. No. 4,761,406, or in combination withone or more bone therapeutic agents such as, without limitation,calcitonin and estrogen.

V. Receptor-Signaling Activities of Compounds of SEQ ID NO: 1 orDerivatives Thereof

A crucial step in the expression of hormonal action is the interactionof hormones with receptors on the plasma membrane surface of targetcells. The formation of hormone-receptor complexes allows thetransduction of extracellular signals into the cell to elicit a varietyof biological responses.

A. Screening for PTH-1 Receptor Antagonists and Agonists

Polypeptides of the invention may be screened for their agonistic orantagonistic properties using the cAMP accumulation assay. Cellsexpressing PTH-1 receptor on the cell surface are incubated with nativePTH(1–84) for 5–60 minutes at 37° C., in the presence of 2 mM IBMX(3-isobutyl-1-methyl-xanthine, Sigma, St. Louis, Mo.). Cyclic AMPaccumulation is measured by specific radio-immunoassay, as describedabove. A compound of SEQ ID NO: 1 or a derivative thereof that competeswith native PTH(1–84) for binding to the PTH-1 receptor, and thatinhibits the effect of native PTH(1–84) on cAMP accumulation, isconsidered a competitive antagonist. Such a compound would be useful fortreating hypercalcemia.

Conversely, a compound of SEQ ID NO: 1 or a derivative thereof that doesnot compete with native PTH(1–84) for binding to the PTH-1 receptor, butwhich still prevents native PTH(1–84) activation of cAMP accumulation(presumably by blocking the receptor activation site) is considered anon-competitive antagonist. Such a compound would be useful for treatinghypercalcemia.

A compound of SEQ ID NO: 1 or a derivative thereof that competes withnative PTH(1–84) for binding to the PTH-1 receptor, and which stimulatescAMP accumulation in the presence or absence of native PTH(1–84) is acompetitive agonist. A compound of SEQ ID NO: 1 or a derivative thereofthat does not compete with native PTH(1–84) for binding to the PTH-1receptor but which is still capable of stimulating cAMP accumulation inthe presence or absence of native PTH(1–84), or which stimulates ahigher cAMP accumulation than that observed by a compound of SEQ ID NO:1 or a derivative thereof alone, would be considered a non-competitiveagonist.

VI. Therapeutic Uses of Compounds of SEQ ID NO: 1 or Derivatives Thereof

Some forms of hypercalcemia and hypocalcemia are related to theinteraction between PTH and PTHrP and the PTH-1 and PTH-2 receptors.Hypercalcemia is a condition in which there is an abnormal elevation inserum calcium level; it is often associated with other diseases,including hyperparathyroidism, osteoporosis, carcinomas of the breast,lung and prostate, epidermoid cancers of the head and neck and of theesophagus, multiple myeloma, and hypernephroma. Hypocalcemia, acondition in which the serum calcium level is abnormally low, may resultfrom a deficiency of effective PTH, e.g., following thyroid surgery.

Nucleic acids of the invention which encode compounds of SEQ ID NO: 1 orderivatives thereof may also be linked to a selected tissue-specificpromoter and/or enhancer and the resultant hybrid gene introduced, bystandard methods (e.g., as described by Leder et al., U.S. Pat. No.4,736,866, herein incorporated by reference), into an animal embryo atan early developmental stage (e.g., the fertilized oocyte stage), toproduce a transgenic animal which expresses elevated levels of compoundsof SEQ ID NO: 1 or derivatives thereof in selected tissues (e.g., theosteocalcin promoter for bone). Such promoters are used to directtissue-specific expression of compounds of SEQ ID NO: 1 or derivativesthereof in the transgenic animal.

In addition, any other amino-acid substitutions of a nature, which donot destroy the ability of the PTH/PTHrP analog to antagonize or agonizethe PTH-1/PTH-2 receptor (as determined by assays known to the skilledartisan and discussed below), are included in the scope of the presentinvention.

By “agonist” is intended a ligand capable of enhancing or potentiating acellular response mediated by the PTH-1 receptor. By “antagonist” isintended a ligand capable of inhibiting a cellular response mediated bythe PTH-1 receptor. Whether any candidate “agonist” or “antagonist” ofthe present invention can enhance or inhibit such a cellular responsecan be determined using art-known protein ligand/receptor cellularresponse or binding assays, including those described elsewhere in thisapplication.

In accordance with yet a further aspect of the invention, there isprovided a method for treating a medical disorder that results fromaltered or excessive action of the PTH-1 receptor, comprisingadministering to a patient a therapeutically effective amount of acompound of SEQ ID NO: 1 or a derivative thereof sufficient to inhibitactivation of the PTH-1 receptor of said patient.

In this embodiment, a patient who is suspected of having a disorderresulting from altered action of the PTH-1 receptor may be treated usingcompounds of SEQ ID NO: 1 or derivatives thereof of the invention whichare a selective antagonists of the PTH-1 receptor. Such antagonistsinclude compounds of SEQ ID NO: 1 or derivatives thereof of theinvention which have been determined (by the assays described herein) tointerfere with PTH-1 receptor-mediated cell activation or otherderivatives having similar properties.

To administer the antagonist, the appropriate compound of SEQ ID NO: 1or a derivative thereof is used in the manufacture of a medicament,generally by being formulated in an appropriate carrier or excipientsuch as, e. g., physiological saline, and preferably administeredintravenously, intramuscularly, subcutaneously, orally, or intranasally,at a dosage that provides adequate inhibition of a compound of SEQ IDNO: 1 or a derivative thereof binding to the PTH-1 receptor. Typicaldosage would be 1 ng to 10 mg of the peptide per kg body weight per day.

In a preferred embodiment, the compound of SEQ ID NO: 1 or a derivativethereof used in the method has a single amino acid deletion at the aminoterminus. In this preferred embodiment, the PTH/PTHrP analog isPTH(2–14)/PTHrP(2–14). In yet another preferred embodiment, the compoundof SEQ ID NO: 1 or a derivative thereof used in the method has a twoamino acid deletion at the amino terminus. In this preferred embodiment,the PTH/PTHrP analog is PTH(3–14)/PTHrP(3–14).

In accordance with yet a further aspect of the invention, there isprovided a method for treating osteoporosis, comprising administering toa patient a therapeutically effective amount of a compound of SEQ ID NO:1 or a derivative thereof, sufficient to activate the PTH-1 receptor ofsaid patient. Similar dosages and administration as described above forthe PTH/PTHrP antagonist, may be used for administration of a PTH/PTHrPagonist, e.g., for treatment of conditions such as osteoporosis, othermetabolic bone disorders, and hypoparathyroidism and related disorders.

In a preferred embodiment, the compound of SEQ ID NO: 1 or a derivativethereof used in the method has an amino acid substitution of alanine forserine at amino acid position 1 of compound of SEQ ID NO: 1. In thisparticular embodiment, the PTH derivative is [Ala¹]PTH(1–14)(SEQ ID NO:5). In another preferred embodiment, the compound of SEQ ID NO: 1 or aderivative thereof used in the method has an amino acid substitution ofhistidine for isoleucine at position 5 of SEQ ID NO: 1. In thisparticular embodiment, the PTHrP derivative is [Ile⁵]PTHrP(1–14). (SEQID NO: 2)

It will be appreciated to those skilled in the art that the inventioncan be performed within a wide range of equivalent parameters ofcomposition, concentration, modes of administration, and conditionswithout departing from the spirit or scope of the invention or anyembodiment thereof.

Having now fully described the invention, the same will be more readilyunderstood by reference to specific examples which are provided by wayof illustration, and are not intended to be limiting of the invention,unless herein specified.

EXAMPLE 1

To begin to identify the minimum length required for bioactivity of PTHand PTHrP, the inventors constructed synthetic peptides based upon thefirst 14 amino acids of native human PTH. As a first step towardsoptimization the inventors replaced the serine at position one byalanine; this substitution, which corresponds to the amino acid found atposition 1 in rat and bovine PTH, as well as in all PTHrP moleculesreported so far (human, bovine, dog, rat, mouse, chicken), results in ameasurable increase in bioactivity over the background level ofbioactivity of the native PTH(1–14) peptide. The C-terminal residue ofthis new peptide, herein called [Ala¹]PTH(1–14), is amidated.

The ability of [Ala¹]PTH(1–14) to stimulate cAMP formation in COS-7cells expressing the cloned human PTH-1 receptor is shown in FIG. 1. Asmall cAMP response can be seen even with the shorter peptide[Ala¹]PTH(1–9). As expected, the carboxy-terminal fragment PTH(15–31)was inactive (FIG. 1). Each of these peptides was inactive in controlCOS-7 cells transected with a DNA vector lacking the PTH-1 receptorgene.

To demonstrate PTH(1–14) specificity, its ability to stimulate cAMPproduction in COS-7 cells transfected with the rat secretin receptor(rSR)—a related Family B receptor that does not bind or respond to PTHwas tested. As shown in the FIG. 6, PTH(1–14) is inactive in cellsexpressing rSR. Thus, the response to PTH(1–14) in COS-7 cells isdependent on PTH-1 receptor expression. PTH(1–14) specificity was alsotested using the porcine renal cell line LLC-PK1, either untransfectedor stably transfected with the human PTH-1 receptor, the LLC-B7 cellline. FIG. 4 shows that the PTH(1–14) response in these cells isdependent on PTH-1 receptor expression.

EXAMPLE 2

As noted above in Example 1, even with the Ser→Ala substitution, the[Ala¹] PTH(1–14) peptide is weaker than native PTH(1–34) (FIG. 1). Thus,additional optimization of the [Ala¹]PTH(1–14) sequence to improvepotency and efficacy was pursued. As part of this optimization process,an alanine-scan of the native PTH(1–14) sequence was performed. In thisstudy, 14 different peptides were synthesized, each 14 amino acids inlength and differing from each other by having one native amino acidreplaced with alanine. This alanine-scan permits the classification ofeach individual residue in the native 1–14 sequence as either criticalfor function (intolerant) or not critical for function (tolerant). Thetolerant residues reside in one well-defined carboxy-terminal segmentthat extends from Asn-10 to His-14, whereas the intolerant residues fallwithin the Ala-1 to His-9 segment (FIG. 2). Note that Ala-1 and Ser-3were not adequately tested in this study, since position 1 is alanine inthe native rat and bovine sequences, and Ser→Ala at position 3 is aconservative substitution. For example, as predicted from thealanine-scan results, the [Ala¹]PTH(1–9) fragment, which contains all ofthe intolerant residues, exhibits some biological activity (FIG. 1).

EXAMPLE 3

The analysis extends to the PTHrP(1–14) sequence as well. The inventorsfound that one monosubstitution, which replaces histidine at thecritical 5 position in PTHrP(1–14) with isoleucine. Thus, in thisparticular embodiment, the pTHrP analog is [Ile⁵]PTHrP(1–14). FIG. 7.shows the cAMP activity results obtained with [Ile5]PTHrP(1–14). LLC-B7cells were treated with the indicated peptide ligand, each at 100 μM,and then intracellular cAMP levels were measured. Substitution ofisoleucine with histidine at the critical 5 position of PTHrP results ina new analog with enhanced potency, relative to native PTHrP(1–14).

1. An isolated nucleic acid molecule consisting of a polynucleotideencoding the sequence of a biologically active peptide selected from thegroup consisting of: (a) X₀₁ValSerGluX₀₂GlnLeuX₀₃HisX₀₄X₀₅GlyLysX₀₆(SEQID NO:1); and (b) a fragments of SEQ ID NO:1, wherein said fragmentconsists of amino acids 1–9, 1–10, 1–11, 1–12, or 1–13; wherein: X₀₁ isSer or Ala; X₀₂ is lie or His; X₀₃ is Met, Leu or NIe; X₀₄ is Asn orAsp; X₀₅ is Leu or Lys; and X₀₆ is His or Ser, provided that saidpeptide is not PTHrP(1–14) (SEQ ID NO:4).
 2. A method for making arecombinant vector comprising inserting a nucleic acid molecule of claim1 into a vector.
 3. A method for making an isolated recombinant hostcell, said method comprises: (a) inserting a nucleic acid molecule ofclaim 1 into a vector to produce a recombinant vector, and (b)introducing the recombinant vector of step (a) into an isolated hostcell.
 4. The method of claim 3, wherein said isolated host cell isprokaryotic.
 5. The method of claim 4, wherein said isolated host cellis bacterial.
 6. The method of claim 3, wherein said isolated host cellis eukaryotic.
 7. The method of claim 6, wherein said isolated host cellis a yeast cell or a mammalian cell.